1. Field of Application
This invention relates to shuttles; and more particularly, telescoping shuttles for material handling.
2. Description of the Prior Art
Material handling equipment, especially unit material handling equipment such as stacker cranes, stacker retrievers, and other load carrying devices, quite often are captive or restricted in their movement along a prescribed path. The restricting means may be a set of rails, that cooperate with path guide structure carried by the equipment to move along a prescribed path of movement that is usually a straight line such as an aisle in a material storage warehouse or area. Other forms of guide means include tracks buried in floors, walls, ceilings and the like that are sensed by equipment carried by the material handling equipment and guide the movement along a prescribed path that may not be a straight line.
Most of such material handling or carrying vehicles are constructed to carry their load in a position which is centrally disposed to facilitate balancing of the carrying vehicle while it is traveling the prescribed path. Central location of the load on the vehicle while the vehicle is moving also enables the vehicle to travel a path which is relatively narrow such an an aisle in a material storage warehouse or a material storage area. When one considers the cost of: buying land for space, constructing buildings, heating, lighting, and air conditioning of space then it becomes quite important to utilize spaces as efficiently as possible. The narrowest possible aisles and paths of movement leave a maximum amount of space for material storage and other purposes such as material handling and manufacturing and assembly areas.
However, the materials to be carried by the vehicle need to be placed upon the vehicle for transport. Many automated and semi-automated vehicles are equipped with material pick-up mechanisms that can be extended from the vehicle to retrieve or otherwise pick-up the goods and which are then retracted to locate the goods in a central location on the vehicle for subsequent transport by the vehicle. Quite often such material pick-up mechanisms take the form of a shuttle or fork which is extended from a central disposition on the vehicle to pick up material and which is retracted back to its central location on the vehicle after it has obtained the material or after it has deposited the material in a designated location.
Increasing the reach of such shuttles or forks has been accomplished by constructing the shuttle with more than one table like carrier and interconnecting the carriers for conjoint movement with respect to the vehicle and with respect to each other in a telescoping manner. Many such shuttles can be extended from and retracted from both one side and the other side of the load carrying vehicle in a bi-directional manner.
Shuttle mechanisms such as those shown in U.S. Pat. Nos. 3,606,039 and 3,632,001, however are relatively complex in construction and operation and utilize an inordinate amount of gearing and drives which add to the expense of manufacture and maintenance. These shuttles, in addition, due to their form of construction and the components required to make the shuttles function are relatively cumbersome and large; especially in the relative height required to house and position the shuttle operating elements. As set forth previously, space costs money and takes time and money to travel along. The higher the shuttle mechanism the less space available to store materials since in many of the available systems the shuttle must move under the material to be stored or retrieved and space must therefore be provided to so accommodate the shuttle mechanism. Shuttle mechanisms, such as those shown in U.S. Pat. Nos. 3,848,754 and 3,892,324 attempt to eliminate as much of the relatively expensive and space consuming chain and gearing as possible but still provide shuttles which are relatively complex in construction and therefore to manufacture, and which also are relatively thick in the height or vertical dimension.